Removable tripod foot with securement

ABSTRACT

Installation of a removable tripod foot is facilitated by a cross-axis aperture in the foot and loosening of the threaded connection of the foot and the tripod&#39;s leg is resisted by a resilient element engaging interfacing surfaces of the foot and the leg.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/594,840, filed Oct. 7, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/436,395, filed Jun. 10, 2019, now U.S. Pat. No.10,473,261, issued Nov. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/294,137, filed Mar. 6, 2018, now U.S. Pat. No.10,359,147, issued Jul. 23, 2019, which application is a continuation ofU.S. patent application Ser. No. 16/101,848, filed Aug. 13, 2018, nowU.S. Pat. No. 10,267,452, issued Apr. 23, 2019, which application is acontinuation of U.S. patent application Ser. No. 15/782,167, filed Oct.12, 2017, now U.S. Pat. No. 10,054,256, issued Aug. 21, 2018, whichapplication is a continuation of U.S. patent application Ser. No.15/605,511, filed May 25, 2017, now U.S. Pat. No. 9,816,662, issued Nov.14, 2017, which application is a continuation of U.S. patent applicationSer. No. 15/293,764, filed Oct. 14, 2016, now U.S. Pat. No. 9,689,525,issued Jun. 27, 2017, which application is a continuation of U.S. patentapplication Ser. No. 13/366,080, filed Feb. 3, 2012, now U.S. Pat. No.9,494,276, issued Nov. 15, 2016, which application claims the benefit ofU.S. Provisional App. No. 61/489,179, filed May 23, 2011.

BACKGROUND OF THE INVENTION

The present invention relates to a removable foot for a tripod and, moreparticularly, to a mechanism to aid in tightening and to resistloosening of a threaded connection between a foot and a leg of a tripod.

Tripods are used for both still and motion photography to providestability and prevent unintended movement of the camera. A tripodreduces camera movement to enable the sharpest image and is especiallyuseful when using a telephoto lens or longer exposure time because anycamera movement while the shutter is open will blur the image. A tripodalso aids in framing an image or in capturing multiple images of thesame scene, for example when bracketing an exposure. A tripod enablescontrolled movement of the camera when panning, facilitating tracking amoving subject with a motion video camera or capturing multiple stillsfor a panoramic image.

Removable feet can increase the utility of a tripod by enabling use ofspecialized feet for particular surfaces and conditions. However,removable feet are commonly attached to a tripod's legs by screw threadswhich can be difficult to tighten and may loosen making the tripodunstable and increasing the likelihood that a foot will be lost. What isdesired, therefore, is a removable tripod foot that is easy to installand resists loosening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a tripod.

FIG. 2 is a perspective view of a claw-type tripod foot.

FIG. 3 is a perspective view of the underside to the claw-type foot ofFIG. 2.

FIG. 4 is a perspective view of a spike tripod foot.

FIG. 5 is an elevation view of a portion of a tripod leg and a removablefoot.

FIG. 6 is a section view of a portion of a tripod leg and a removablefoot.

FIG. 7 is an elevation view of a portion of a tripod leg and a removablefoot of a second embodiment.

FIG. 8 is an enlarged view of a portion of the section of FIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring in detail to the drawings where similar parts are identifiedby like reference numerals, and, more particularly to FIG. 1, a tripod20 is useful for both still and motion photography. Typically, a tripodcomprises an apex mount 22 including a mechanism, such as a threadedstud 24, for securing a camera or an intermediate interface, such as aball head or panoramic element, to which a camera can be secured. Theapex mount 22 is secured to an apex structure 26 which is also theanchor point for the three legs 28 of the tripod. Each of the legs istypically secured to the apex structure 26 by a pivot joint 30 enablingthe legs to be pivoted toward each other for transport and pivoted apartwhen the tripod is deployed for use. The legs 28 commonly comprise aplurality of leg sections, such as the three leg sections 32, 34, and36, that telescope together to reduce the length of the collapsed tripodfor transport or to enable adjustment of the height of the deployedtripod or compensation for an irregular supporting surface. A lockingmechanism 38 which may be actuated by twisting secures the relativepositions of the telescoping tube sections. Photographic tripods arepreferably light weight and compact to facilitate transportation and theleg sections commonly comprise tubes of light weight materials such asaluminum or carbon fiber.

Tripod feet 40 provide the interface between the legs of the tripod andthe surface on which the tripod will be supported. The tripod feetcommonly have a curved lower surface 42 which is often covered withrubber or plastic to resist sliding on a floor or other supportingsurface. While the feet may be permanently affixed to the legs of thetripod, the feet are often removable enabling more specialized feet tobe substituted when desired. Referring FIGS. 2 and 3, for example, onetype specialized tripod foot is a claw foot 50 having body 52 comprisinga crenated wall 54 with a plurality of facets 56 along the lower edge.The sharp edges 58 at the intersections of the facets are intended tobite into a hard, rough surface and secure the tripod even if thesurface is wet. Referring to FIG. 4, another type of specialized tripodfoot is a spike foot 70. The pointed end portion 72 of the foot'sspike-like body 76 is intended to penetrate loose surface materialproviding additional support on shifting surfaces or in strong winds.

Referring to also FIGS. 5 and 6, replaceable tripod feet are commonlyaffixed to the leg of the tripod by screwing a threaded stud 80projecting from the foot into a threaded aperture 82 in a ferrule 84which is secured to the end of a tubular leg section 86. On the otherhand, referring to FIG. 7, the gender of the threads in the ferrule andthe foot may be reversed with male threads of a threaded stud 90projecting from the ferrule to engage female threads in an aperture 92in the foot. While a threaded connection makes replacement straightforward, it can be difficult to fully tighten the threaded connection.The feet can also loosen as a result of cyclic loads and vibration asthe tripod is repeatedly deployed or moved across a supporting surface;a condition that is exacerbated by the difficulty in tightening thefeet. When the threaded feet loosen, the tripod becomes unstable and thefeet may eventually become detached from the tripod. To prevent theremovable feet from loosening, a liquid thread locker is commonlyapplied to the threads but this is time consuming and the container mayleak damaging other equipment in a camera bag. On the other hand,threaded connections with prevailing torque features increase the torquerequired to tighten, as well as loosen, the connection making tighteningand removal more difficult and the features may wear and becomeineffective with repeated use. The applicants concluded that a mechanismthat would permit removable tripod feet to be easily tightened but wouldreliably resist loosening would substantially improve the utility of atripod.

The removable feet 50, 70 for use with the tripod 20 include a resilientelement 94 at the interface between the foot and the ferrule 84 securedto the end of the tripod's leg 28. As illustrated in FIG. 5, theresilient element 94 may be supported by the leg engaging surface 60 ofthe removable foot, but, referring to FIG. 7, the resilient element 94could be applied to the foot engaging surface 96 of the ferrule 84. Theresilient element increases friction between the interfacing surfaces ofthe foot and the ferrule to resist loosening of the threaded connection.While the elastomeric element could have any shape and could be appliedto the respective surface, it is, preferably, a toroidal element, and,more preferably, an elastomeric o-ring installed in a groove 98 in oneof the interfacing surfaces 60, 96. Referring also to FIG. 8, the groove98 has an inner wall 99 which is undercut at an angle 101. The diameterof the groove at the point of intersection of the inner wall with theinterfacing surface 60 is slightly greater than the inner diameter ofthe resilient element 94. When the resilient element is installed in thegroove it must be stretched slightly. When the resilient element isreleased in the groove, it returns to its original size and is trappedin the groove against the sloping inner wall. On the other hand, theresilient element could be retained in the groove by an outer wall thatsloped to a diameter, at the interfacing surface, that is slightlysmaller than the outer diameter of the resilient element. A portion ofthe resilient element projects proud of the respective leg engagingsurface 60 or foot engaging surface 96 so that the resilient element iscompressed when the threaded connection is tightened. While an o-ring isinexpensive, the dimensions and characteristics of o-rings are carefullycontrolled and the force exerted by the o-ring is predictable enablingthe foot to be tightened so that the interfacing surfaces 60 and 96 comein contact. Contact between the rigid leg engaging and foot engagingsurfaces enhances the stability of the foot and the tripod and increasesfriction in the threaded connection which resists loosening. Thecompressed resilient element exerts a resilient separating force at theinterfacing surfaces maintaining friction in the engaged screw threadsduring vibration and cyclic loading and resisting loosening of thethreaded connection. Since the resilient element 94 does not come incontact with both of the interfacing surfaces until the surfaces areproximate each other, the foot screws easily into the ferrule for amajor portion of the length of the threaded connection.

To compress the resilient element and bring the leg engaging surfaceinto contact with the foot engaging surface, an aperture(s) 74 whichextends substantially normal to the longitudinal axis of the threadedelement in the foot is provided in the body of the foot. A tool, such asa rod, an Allen wrench 100 or the shank of a screw driver can beinserted into the aperture providing the necessary leverage to fullytighten the threaded connection.

The resilient element at the interfacing surfaces of a removable footand a tripod leg and a cross-axis aperture facilitates installation ofthe foot and resists loosening of the threaded connection.

The detailed description, above, sets forth numerous specific details toprovide a thorough understanding of the present invention. However,those skilled in the art will appreciate that the present invention maybe practiced without these specific details. In other instances, wellknown methods, procedures, components, and circuitry have not beendescribed in detail to avoid obscuring the present invention.

All the references cited herein are incorporated by reference.

The terms and expressions that have been employed in the foregoingspecification are used as terms of description and not of limitation,and there is no intention, in the use of such terms and expressions, ofexcluding equivalents of the features shown and described or portionsthereof, it being recognized that the scope of the invention is definedand limited only by the claims that follow.

We claim:
 1. A foot for a tripod comprising: (a) a body including aninterface surface including a portion arranged to engage a terminalportion of a leg of a tripod and an elongate threaded portion arrangedsubstantially normal to the portion of the interface surface; (b) aresilient element engaging the interface surface; (c) wherein saidresilient element extends proud of the portion of said interface surfacearranged to engage the leg of the tripod; (d) wherein said interfacesurface includes an outer peripheral edge and said resilient element issized such that at least a portion is within said outer peripheral edgeof said interface surface when engaged therewith; (e) wherein saidresilient element has an outer diameter and further said body includes abody outer peripheral surface with an outer diameter proximate saidouter peripheral edge, where the resilient element outer diameterextends proud of the body outer peripheral surface; (f) wherein saidbody includes a spike to engage said surface supporting said tripod. 2.The foot for said tripod of claim 1 wherein said spike is circular incross section.
 3. The foot for said tripod of claim 2 wherein said spikeis tapering along a length of said spike.
 4. The foot for said tripod ofclaim 3 wherein said body defines an opening in said body.
 5. The footfor said tripod of claim 4 wherein said body defines said opening insaid body at a location directly above a terminal portion of said spike.6. The foot for said tripod of claim 5 wherein said opening is alignedwith said elongate threaded portion.
 7. The foot for said tripod ofclaim 1 wherein the interface surface includes a portion defining acircular groove and the resilient element comprises an elastomerictoroid retained in the groove with a portion of a surface of theresilient element projecting proud of the portion of the interfacesurface arranged to engage the leg of a tripod.
 8. The foot for saidtripod of claim 1 wherein said elongate threaded portion of said bodycomprises a portion defining a threaded aperture.
 9. The foot for saidtripod of claim 1 further comprising said tripod.
 10. The foot for saidtripod of claim 1 wherein said body defines an opening in said body.